The present invention is directed to improved devices and methods for reducing infection associated with the collection of body fluid from a human or animal subject and the introduction of fluids into the body.
In modern medical practice, it is often desirable either to drain fluids from or to introduce fluids into a human or animal subject under sterile conditions. For example, it is a routine practice to catheterize hospital patients for urinary or closed wound drainage. Similarly, a number of body cavities, such as the urinary bladder and the peritoneal cavity, for example, are routinely irrigated during treatment of various disorders. In these and other similar situations, the continued sterility of all associated devices used for passing fluid to and from the body may be critically important, for a contaminated device will, in many cases, lead to infection of the patient.
Two commonly used techniques for treatment of patients who have experienced significant renal failure utilize the transfer of body fluids and solutions through conduit systems to and from the patient. The traditional therapy has been hemodialysis, where the patient's blood is passed through filters that would remove the waste material from the patient's bloodstream. The second technique is peritoneal dialysis, where solutions are cycled into and out of the peritoneal cavity of the patient and wastes are removed with the spent solution.
Both techniques operate by the principles of diffusion across semipermeable membranes. In the case of peritoneal dialysis, the membrane that is used is the patient's peritoneal membrane. Although it is not as efficient as hemodialysis, peritoneal dialysis offers several advantages that has enhanced its desirability. For example, automated devices have been developed that allow a patient to undergo a dialysis treatment at night while the patient is asleep. Utilizing these automated devices allows the patient great mobility and freedom of time.
Peritoneal dialysis can be accomplished in several different modes. In Continuous Ambulatory Peritoneal Dialysis ("CAPD"), the infusion of solution into and out of the peritoneal cavity is accomplished while the patient functions normally throughout the day. The obvious disadvantages of CAPD are the cumbersome devices that must be worn by the patient. Examples of CAPD systems are presented in U.S. Pat. Nos. 5,747,822 of Peabody and 4,620,846 of Goldberg et al.
Two types of peritoneal dialysis therapies that are particularly suitable for use with automated systems are Intermittent Peritoneal Dialysis ("IPD") and Continuous Cycling Peritoneal Dialysis ("CCPD"). In IPD, large amounts of dialysis solution (up to 40 liters) are cycled through the patient's peritoneal cavity over a 4 to 24 hour period. In CCPD, the dialysis treatment is more or less continuous, with dwell times of 3 to 4 hours at night and then throughout the waking time of the patient a single charge of dialysis solution is retained within the patient. There are certain advantages to each of these two different therapy techniques.
In both IPD and CCPD, an automated dialysis apparatus operates in generally the same manner. The dialysis solution and tubing administration set is integrated with the valving, heating and control functions associated with the automated apparatus. In many of the systems, premeasured amounts of dialysis solution are either pumped or delivered by gravity flow to a heating station. At the heating station the solution is warned to body temperature in order to prevent the uncomfortable sensation of introducing room temperature or cooler solution into the peritoneal cavity. The warmed solution is then delivered from the dialysis station to the patient's peritoneal cavity via a fluid delivery line which is essentially flexible tubing connected to a catheter at the end that enters the patient's peritoneal cavity. After a period of time, "dwell periods", the solution is drained from the patient into a drain container.
In IPD, a large amount of solution is cycled in this manner over a relatively short period of time. Once treatment is completed, the patient is unencumbered for at least a few days. A disadvantage is the large amount of dialysis solution that must be utilized. Bags containing 40 liters of solution can be difficult to lift for a patient in a weakened condition.
In CCPD, the same efficiency of results is obtained by increasing the dwell time of the dialysis solution within the peritoneal cavity. The total amount of solution required can therefore be significantly reduced. The obvious disadvantage is that there is less "down time" from the treatment.
The delivery line in peritoneal therapy, as indicated above, generally includes flexible tubing to transfer fluid to and from the catheter site, a catheter to enter the peritoneal cavity, and a catheter connector between the tubing and the catheter. A releasable manual clamp is threaded onto the tubing to occlude the tubing as it is connected to the catheter through the catheter connector. Also included is a permanent manual clamp to permanently occlude the tubing when the dialysis is completed so that the tubing can be disconnected from the catheter connector without any spilling of the drained fluids. A wide variety of tubing sets are known in the art and are used in a number of different applications. For example, see the tubing administration set described in Ser. No. 425,879 by Topaz et al, assigned to the assignee of the present invention and hereby incorporated by reference.
Upon completion of the CCPD for example, it is necessary to disconnect the patient from the tubing set. This is normally accomplished by permanently occluding the delivery line by closing the permanent manual clamp, and then cutting the tubing on the side of the permanent manual clamp away from the patient. The permanent manual clamp thereby occludes the delivery line on the patient side in order to prevent any spilling of the drained fluid. After the tubing is cut, a clamp on the catheter is used to occlude the catheter, and the stub of the tubing is removed from the catheter. When the CCPD is repeated, a new tube is connected to the catheter, the catheter clamp is loosened, and the process is repeated.
The cutting of the delivery line is normally accomplished with a pair of scissors or a knife. This, of course, necessitates that the scissors or knife be available. Moreover, because CCPD therapy is purposely designed so that it can be administered by the patient himself without the help of a nurse or other person, the scissors or knife must be located so that the patient can reach them while still connected to the tubing set.
Another problem with a system in which the delivery line is cut with a knife or scissors is that there is no indicator on the delivery line of where it should be cut. A frequent problem, therefore, is that the patient accidentally cuts the delivery line on the patient side of the clamp, thereby spilling drain fluid. Even worse, the patient sometimes accidentally cuts the catheter rather than the tubing, thereby requiring the removal of the damaged catheter and the insertion of a new catheter.
After the tubing is cut, a clamp on the catheter is used to occlude the catheter and the stub of the tubing is removed from the catheter. When the CCPD is repeated, a new tube is connected to the catheter, the catheter clamp is loosened, and the process is repeated.
A continuing dilemma exists in systems presently used in a variety of medical fluid conduit apparatus whether attended by professional assistance or manipulated by the patient. Frequently, the professional assistant is required to connect and disconnect body fluid and medical solution conduits several times a day while performing other patient care obligations simultaneously. A continuing need exists for breakable tubing coupling apparatus and methodology for both the professional assistant and the weakened patient performing self-treatment. Neither individual has the ability or the flexibility to utilize extra equipment such as knives or scissors to cut conduit or tubing. In addition, the position of the tubing cut is generally critical, thus the need for preconditioned apparatus for breakable tubing coupling applications are most desirable.